Pprocess and apparatus for effecient recovery of dichlorohydrins

ABSTRACT

A process and apparatus is disclosed for recovering dichlorohydrins from a hydrochlorination reactor effluent stream comprising dichlorohydrins, one or more compounds selected from esters of dichlorohydrins, monochlorohydrins and/or esters thereof, and multihydroxylated-aliphatic hydrocarbon compounds and/or esters thereof, and optionally one or more substances comprising water, chlorinating agents, catalysts and/or esters of catalysts. The reactor effluent stream is distilled to produce a dichlorohydrin-rich vapor phase effluent stream. The dichlorohydrin-rich vapor phase effluent stream is cooled and condensed in two unit operations conducted at two different temperatures and a portion of the liquid phase effluent stream produced by the first unit operation is recycled to the distillation step for reflux. Product streams produced by the process and apparatus are suitable for further processing in a further unit operation, such as dehydrochlorination. Advantages include recovery of high purity dichlorohydrins, more efficient recovery of dichlorohydrins, and reduced capital investment in the recovery equipment.

BACKGROUND OF THE INVENTION

The present invention relates to processes and apparatus for recoveringdichlorohydrins from a mixture comprising the same such as the effluentgenerated by a process for converting multihydroxylated-aliphatichydrocarbon compound(s) and/or ester(s) thereof to chlorohydrins.

Dichlorohydrins are useful in preparing epoxides such asepichlorohydrin. Epichlorohydrin is a widely used precursor to epoxyresins. Epichlorohydrin is a monomer which is commonly used for thealkylation of para-bisphenol A. The resultant diepoxide, either as afree monomer or oligomeric diepoxide, may be advanced to high molecularweight resins which are used for example in electrical laminates, cancoatings, automotive topcoats and clearcoats.

Glycerin is considered to be a low-cost, renewable feedstock that is aco-product of the biodiesel process for making fuel. It is known thatother renewable feedstocks such as fructose, glucose and sorbitol can behydrogenolized to produce mixtures of vicinal diols and triols, such asglycerin, ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycoland the like. With abundant and low cost glycerin or mixed glycols,economically attractive processes for recovering dichlorohydrins fromeffluents produced by the above processes are desired.

A process is known for the conversion of glycerol (also referred toherein as “glycerin”) to mixtures of dichloropropanols, compounds I andII, as shown in Scheme 1 below. The reaction is carried out in thepresence of anhydrous HCl and an acetic acid (HOAc) catalyst with waterremoval. Compounds I and II can then be converted to epichlorohydrin viatreatment with caustic or lime.

Various processes using the above chemistry in Scheme 1 have beenreported in the prior art. For example, epichlorohydrin can be preparedby reacting a dichloropropanol such as 2,3-dichloro-1-propanol or1,3-dichloro-2-propanol with base. Dichloropropanol, in turn, can beprepared at atmospheric pressure from glycerol, anhydrous hydrochloricacid, and an acid catalyst. A large excess of hydrogen chloride (HCl)was recommended to promote the azeotropic removal of water that isformed during the course of the reaction.

WO 2006/020234 A1 describes a process for conversion of glycerol or anester or a mixture thereof to a chlorohydrin, comprising the step ofcontacting a multihydroxylated-aliphatic hydrocarbon compound, an esterof a multihydroxylated-aliphatic hydrocarbon, or a mixture thereof witha source of a superatmospheric partial pressure of hydrogen chloride toproduce chlorohydrins, esters of chlorohydrins, or mixtures thereof inthe presence of an organic acid catalyst. This process is referred toherein as a “dry process” because the process uses dry hydrogen chlorideand the source of water in the process is essentially only the watergenerated as a co-product in the reaction. In the dry process,azeotropic removal of water, via a large excess of hydrogen chloride, isnot required to obtain high chlorohydrins yield. WO 2006/020234 A1further teaches that separation of the product stream from the reactionmixture may be carried out with a suitable separation vessel such as oneor more distillation columns, flash vessels or extraction columns WO2006/020234 A1 does not describe a specific process and apparatus forefficient recovery of dichlorohydrins.

WO 2005/021476 A1 describes a process using atmospheric partial pressureof hydrogen chloride, acetic acid as the catalyst, and a cascade ofloops, preferably three loops, each loop consisting of a reactor and adistillation column in which water of reaction, residual hydrogenchloride and dichloropropanol are removed from the reaction effluent.This process for reaction and distillation requiring a cascade ofreactor/distillation loops is very expensive as it requires severalreactor/column loops in the process. Furthermore, valuable acetic acidis lost with the distillate during distillation, resulting in a largerate of acetic acid consumption in the process, making the processexpensive to operate.

EP 1 752 435 A1 (also published as WO 2005/054167) as well as EP 1 762556 A1 disclose another process for producing a chlorohydrin by reactionbetween glycerol and aqueous hydrogen chloride to producedichlorohydrins. The process disclosed in EP 1 752 435 A1 and EP 1 762556 A1 is referred to herein as a “wet process” because the process notonly produces water from the reaction but also adds a large amount ofwater into the process via the aqueous hydrogen chloride reactant. Thewet process described in the above prior art requires three separationcolumns; a distillation column for distillation of the reactor's gasphase to remove the large excess of water from the reaction medium whilekeeping hydrogen chloride in the process; a stripper column to stripwater and hydrogen chloride from the reactor's liquid phase; and yetanother distillation or a stripping column for recoveringdichloropropanol from the liquid phase exiting the stripper. Somedichloropropanol is removed from the reaction medium in the first andthe second separation columns because of existence of a pseudoazeotropeamong dichloropropanol, water and hydrogen chloride. The main fractionof dichloropropanol is collected from the top of the distillation orstripping column, the third separation column. The column residue isrecycled to the reactor. This process has very high energy consumptionbecause of the need to evaporate a large amount of water from theprocess. This process is unsuitable for efficiently recoveringdichlorohydrins from a reaction effluent of a dry process.

CN 101007751A describes another process that combines wet and dryprocesses with two reactors in series, in which a tubular reactor isused as the first reactor and a foaming-tank reactor is used as thesecond reactor. Aqueous hydrogen chloride is fed to the tubular reactorand gaseous hydrogen chloride is fed to the foaming-tank reactor. Inertimpurities are added to the hydrogen chloride in order to improveefficiency of stripping water from the reaction mixture in thefoaming-tank reactor. This process requires much greater use of HCl thanthat required for reaction and dichlorohydrin yield is relatively low.

Opportunities remain to further improve recovery of dichlorohydrins,from a dichlorohydrins comprising stream, in a form that can be used insubsequent conversions, such as the conversion to epichlorohydrin.Accordingly, it is desired to provide improved processes and apparatuswith specific steps for separating the product dichlorohydrin from thereaction effluent of hydrochlorination of multi-hydroxylated aliphatichydrocarbon compounds. It is also desired provide a significantreduction in capital and operating cost of a process for recoveringdichlorohydrins which can be integrated into a glycerinehydrochlorination process as well as glycerine to epichlorohydrinprocess. It is further desired to provide a process that uses only onedistillation column to recover dichlorohydrins from a dichlorohydrinscomprising stream and can provide a high purity dichlorohydrin stream.

SUMMARY OF THE INVENTION

The present invention provides the desired process for improved recoveryof dichlorohydrins, from a dichlorohydrins comprising stream that doesnot have the disadvantages of the prior art processes.

One aspect of the present invention is a process for recoveringdichlorohydrin(s) from a mixture comprising dichlorohydrin(s), water,one or more compounds selected from monochlorohydrin(s), ester(s) ofchlorohydrin(s), and multihydroxylated-aliphatic hydrocarbon compound(s)and/or ester(s) thereof, and, optionally, one or more substancescomprising chlorinating agent(s), catalyst(s), ester(s) of catalyst(s),and/or heavy byproducts, wherein the process comprises:

-   -   (a) distilling or fractionating the mixture under reflux        conditions to separate from the mixture a first vapor phase        effluent stream having a first temperature and comprising at        least dichlorohydrin(s) and water;    -   (b) cooling the first vapor phase effluent stream of step (a)        nonadiabatically to a second temperature lower than the first        temperature of step (a) to condense a fraction of the first        vapor phase effluent stream of step (a) to produce a first        condensed liquid-phase effluent stream and a second vapor phase        effluent stream having the second temperature;    -   (c) separating the first condensed liquid-phase stream of        step (b) into a first fraction and a second fraction;    -   (d) recycling the first fraction of step (c) to step (a) as        reflux for step (a); and    -   (e) cooling the second vapor phase effluent stream of step (b)        nonadiabatically to a third temperature lower than the second        temperature of the second vapor phase effluent stream to        condense at least a fraction of the second vapor phase effluent        stream of step (b) to produce a second condensed liquid-phase        effluent stream and, optionally, a third vapor phase effluent        stream having the third temperature,        wherein the second temperature of step (b) is selected to        produce a first condensed liquid-phase effluent stream        containing more than 50 weight-percent dichlorohydrin.

Another aspect of the present invention is an apparatus suitable forproducing dichlorohydrin(s) from multihydroxylated-aliphatic hydrocarboncompound(s) and/or ester(s) thereof comprising:

-   -   (1) A reactor system suitable for carrying out hydrochlorination        of multi-hydroxylated aliphatic hydrocarbon compound(s) and/or        ester(s) thereof comprising one or more reactors connected in        series or in parallel;    -   (2) a separation system comprising at least one liquid-vapor        contacting device (41) suitable for distillation and/or        fractionation of a reactor effluent stream obtainable from the        reactor system (30) and, optionally, at least one flash vessel;    -   (3) a first condensation system comprising a first cooling        device (51) and optionally a first reservoir (52) connected to        the cooling device (51) for accumulation of condensate from the        first cooling device (51); and    -   (4) a second condensation system comprising a second cooling        device (61) and optionally (a) a second reservoir (62) connected        to the second cooling device (61) for accumulation of condensate        from the second cooling device (61) and/or (b) a liquid-liquid        phase separation device (66) connected to the second cooling        device (61) for separating a liquid phase comprising aqueous and        organic components into an aqueous phase and an organic phase        separate from the aqueous phase,        wherein the reactor system (30) is connected to the separation        system (40) for conducting a reactor effluent stream (34) from        the reactor system (30) to the separation system (40) for        distillation and/or fractionation of the reactor effluent stream        (34),        the separation system (40) is connected to the first        condensation system (50) for conducting a first vapor phase        distillation and/or fractionation effluent stream (47) from the        separation system (40) to the first condensation system (50),        the first condensation system (50) is connected to the second        condensation system (60) for conducting a second vapor phase        effluent stream (57) from the first condensation system (50) to        the second condensation system (60), and        the first condensation system (50) is connected to the        separation system (40) for conducting a fraction (54, 55) of a        first condensed liquid-phase effluent stream (53) from the first        condensation system (50) to the separation system (40).

BRIEF DESCRIPTION OF THE DRAWINGS

For the purpose of illustrating the present invention, the drawings showembodiments of the present invention which are presently preferred.However, it should be understood that the present invention is notlimited to the precise arrangements and instrumentalities shown in thedrawings. In the accompanying drawings, like reference numerals are usedto denote like parts throughout the several drawings.

FIG. 1 is a process diagram illustrating a first embodiment of thepresent invention.

FIG. 2 is a process diagram illustrating a second embodiment of thepresent invention.

DETAILED DESCRIPTION OF THE INVENTION Definitions

As used herein, the term “multihydroxylated-aliphatic hydrocarboncompound” (abbreviated hereafter as “MAHC”) refers to a compound thatcontains at least two hydroxyl groups covalently bonded to two separatevicinal carbon atoms and no ether linking groups. They contain at leasttwo sp3 hybridized carbons each bearing an OH group. The MAHCs includeany vicinal-diol (1,2-diol) or triol (1,2,3-triol) containinghydrocarbon including higher orders of contiguous or vicinal repeatunits. The definition of MAHC also includes for example one or more1,3-1,4-, 1,5- and 1,6-diol functional groups as well. Geminal-diols,for example, are precluded from this class of MAHCs.

The MAHCs contain at least 2, preferably at least 3, up to about 60,preferably up to 20, more preferably up to 10, even more preferably upto 4, and yet more preferably up to 3, carbon atoms and can contain, inaddition to aliphatic hydrocarbon, aromatic moieties or heteroatomsincluding for example halide, sulfur, phosphorus, nitrogen, oxygen,silicon, and boron heteroatoms; and mixtures thereof. The MAHCs may alsobe a polymer such as polyvinyl alcohol.

The terms “glycerin”, “glycerol” and “glycerine”, and esters thereof,may be used as synonyms for the compound 1,2,3-trihydroxypropane, andesters thereof.

As used herein, the term “chlorohydrin” means a compound containing atleast one hydroxyl group and at least one chlorine atom covalentlybonded to two separate vicinal aliphatic carbon atoms and no etherlinking groups. Chlorohydrins are obtainable by replacing one or morehydroxyl groups of MAHCs with covalently bonded chlorine atoms viahydrochlorination. The chlorohydrins contain at least 2, and preferablyat least 3, up to about 60, preferably up to 20, more preferably up to10, even more preferably up to 4, and yet more preferably up to 3,carbon atoms and, in addition to aliphatic hydrocarbon, can containaromatic moieties or heteroatoms including for example halide, sulfur,phosphorus, nitrogen, oxygen, silicon, and boron heteroatoms, andmixtures thereof. A chlorohydrin that contains at least two hydroxylgroups is also a MAHC.

As used herein, the term “monochlorohydrin” means chlorohydrin havingone chlorine atom and at least two hydroxyl groups, wherein the chlorineatom and at least one hydroxyl group are covalently bonded to twoseparate vicinal aliphatic carbon atoms (referred to hereafter by theabbreviation “MCH”). MCH produced by hydrochlorination of glycerin orglycerin esters includes, for example, 3-chloro-1,2-propanediol and2-chloro-1,3-propanediol.

As used herein, the term “dichlorohydrin” means chlorohydrin having twochlorine atoms and at least one hydroxyl group, wherein at least onechlorine atom and at least one hydroxyl group are covalently bonded totwo separate vicinal aliphatic carbon atoms (referred to hereafter bythe abbreviation “DCH”). Dichlorohydrins produced by hydrochlorinationof glycerin or glycerin esters include 1,3-dichloro-2-propanol and2,3-dichloro-1-propanol.

As used herein, the expression “under hydrochlorination conditions”means conditions capable of converting at least 1 wt. %, preferably atleast 5 wt. %, more preferably at least 10 wt. % of MAHCs, MCHs, andesters of MAHCs and MCHs present in a mixture and/or feed stream intoDCH(s) and/or ester(s) thereof.

As used herein, the term “byproduct(s)” means compound(s) that is/arenot chlorohydrin(s) and/or ester(s) thereof and/or chlorinating agent(s)and that do not form chlorohydrin(s) and/or ester(s) thereof under thehydrochlorinating conditions selected according to the presentinvention.

The expression “heavy byproduct(s)” refer to oligomers of mixture (a)components, such as oligomers of MAHCs and/or esters thereof andoligomers of chlorohydrins and/or esters thereof, and derivatives ofsuch oligomers, such as esters thereof, chlorinated oligomers, and/orchlorinated esters thereof, having a number average molecular weightequal to or greater than the number average molecular weight of theoligomer, such as chlorinated oligomers. The terms chlorohydrin(s),MCH(s) and DCH(s), and ester(s) thereof, are not intended to includeheavy byproducts.

The term “epoxide” means a compound containing at least one oxygenbridge on a carbon-carbon bond. Generally, the carbon atoms of thecarbon-carbon bond are contiguous and the compound can include otheratoms than carbon and oxygen atoms, like hydrogen and halogens, forexample. Preferred epoxides are ethylene oxide, propylene oxide,glycidol and epichlorohydrin.

As used herein, the expression, “liquid-phase” refers to a continuousintermediate phase between gas phase and a solid phase that mayoptionally comprise a minor amount of gas and/or solid discretephase(s). The liquid phase may comprise one or more immiscible liquidphases and may contain one or more dissolved solids, such as one or moreacids, bases, or salts.

As used herein, the expression “vapor phase” refers to a continuousgaseous phase that may optionally comprise a minor amount of liquidand/or solid discrete phase(s) (e.g., aerosol). The vapor phase may be asingle gas or a mixture, such as a mixture of two or more gases, two ormore liquid discrete phases, and/or two or more solid discrete phases.

As used herein, the expression “liquid-vapor contacting device” refersto devices that serve to provide the contacting and development of atleast one interfacial surface between liquid and vapor in the device.When the liquid-vapor contacting device is intended for distillingand/or fractionating the components of a feedstream, the liquid-vaporcontacting device (41) preferably has a bottom end generally indicatedby numeral (42) and a top end, generally indicated by numeral (43)suitable for applying a gradually decreasing temperature gradient fromthe bottom end to the top end to substances within the column. Examplesof liquid-vapor contacting devices include plate column, packed column,wetted-wall (falling film) column, spray chamber, heat exchanger or anycombination thereof. Examples of devices comprising plate columns andpacked columns include distillation columns, fractionation columns, andstripping columns.

As used herein, the expression “liquid distributor” means a device thatspreads the liquid uniformly across the top of the packing in a packedbed column. Uniform distribution of liquid at the top of the packed bedis important for efficient column operation.

As used herein, the term “cooling device” means a system for removingheat from a process fluid via a secondary fluid physically separatedfrom the process fluid, such as a condenser. The process fluid and thesecondary fluid may each be a vapor, a liquid, or a combination ofliquid and vapor. Cooling may be a unit operation external to adistillation column or it may be a unit operation internal to adistillation column. The physical separation may be in the form of tubesand the condensation may be carried out on the inside or outside of thetubes. Cooling preferably comprises nonadiabatic cooling and the coolingdevice is therefore preferably a nonadiabatic cooling device.

Mixture Processed in Step (a)

The mixture processed in step (a) may be obtained directly or indirectlyfrom any hydrochlorination process well-known in the art. For example,German Patent No. 197308 teaches a process for preparing a chlorohydrinby the catalytic hydrochlorination of glycerin by means of anhydroushydrogen chloride. WO 2005/021476 discloses a continuous process forpreparing the dichloropropanols by hydrochlorination of glycerin and/ormonochloropropanediols with gaseous hydrogen chloride with catalysis ofa carboxylic acid. WO 2006/020234 A1 describes a process for conversionof a glycerol or an ester or a mixture thereof to a chlorohydrin,comprising the step of contacting a MAHC, an ester of a MAHC, or amixture thereof with a source of a superatmospheric partial pressure ofhydrogen chloride to produce a chlorohydrin, an ester of a chlorohydrin,or a mixture thereof in the presence of an organic acid catalyst withoutsubstantially removing water. The above references are herebyincorporated herein by reference with respect to the above-describeddisclosures.

In an exemplifying hydrochlorination process, MAHC and ahydrochlorination catalyst are charged to the hydrochlorination reactor.Then a chlorinating agent such as hydrogen chloride is added to thereactor. The reactor pressure is adjusted to the desired pressure andthe reactor contents are heated to the desired temperature for thedesired length of time. After completion of the hydrochlorinationreaction or while carrying out the hydrochlorination reaction, thereactor contents as a reaction effluent stream is discharged from thereactor and fed directly, or indirectly via another reactor or otherintervening step, to a separation system comprising a DCH recoverysystem according to the present invention and optionally including otherseparation systems or equipment, such as a flash vessel and/or reboiler.

The hydrochlorination reaction above may be carried out in one or morehydrochlorination reactor vessels such as a single or multiplecontinuous stirred tank reactors (referred to hereafter by theabbreviation “CSTR”), single or multiple tubular reactor(s), plug flowreactors (referred to hereafter by the abbreviation “PFR”), orcombinations thereof. The hydrochlorination reactor can be, for example,one reactor or multiple reactors connected with each other in series orin parallel including, for example, one or more CSTRs, one or moretubular reactors, one or more PFRs, one or more bubble column reactors,and combinations thereof.

In a preferred embodiment, part or all of the hydrochlorination effluentstream is a feed stream from a PFR. A PFR is a type of reactor that hasa high length/diameter (L/D) ratio and has a composition profile alongthe length of the reactor. The concentration of the reactants being fedinto the PFR decreases from inlet to the outlet along the flow path ofthe PFR and the concentration of the products or the intermediateproducts increases from inlet to the outlet along the flow path of thePFR. In the case of hydrochlorination of glycerol, the concentration ofHCl and glycerol decreases from inlet of the PFR to outlet of the PFRwhile the total concentration of chlorohydrins increases from inlet ofthe PFR to the outlet of the PFR.

The equipment useful for conducting the hydrochlorination reaction maybe any well-known equipment in the art and should be capable ofcontaining the reaction mixture at the conditions of thehydrochlorination. Suitable equipment may be fabricated of materialswhich are resistant to corrosion by the process components, and mayinclude for example, metals such as tantalum, suitable metallic alloys(particularly nickel-molybdenum alloys such as Hastalloy C®), orglass-lined equipment, for example.

In addition to DCH(s), one or more of the unreacted MAHC(s) and/orchlorination agent(s), reaction intermediates such as MCH(s), MCHester(s), and/or DCH ester(s), catalyst(s), ester(s) of catalyst(s),water, and/or heavy byproduct(s) may be present in mixture (a). Arecycle process is preferred in which one or more of the unreactedMAHC(s), ester(s) of MAHC(s) and/or chlorination agent(s), reactionintermediates such as MCH(s), MCH ester(s), DCH ester(s), and othersubstances such as catalyst(s) and ester(s) of catalyst(s), arepreferably recycled to a prior step in the process, such as to at leastone hydrochlorination reactor for further hydrochlorination. Inparticular, a liquid higher boiling fraction comprising a residue of thedistilling or fractionating step containing one or more of MAHC(s),MCH(s), catalyst(s), and/or ester(s) of one or more MAHC(s), MCH(s),DCH(s) and/or catalyst(s), and preferably a combination of two or morethereof, is recycled to the hydrochlorination step, such as by recyclingthe higher boiling fraction to one or more reactor(s). Such recycleprocess(es) is preferably continuous. In this manner, raw materialefficiencies are maximized and/or catalysts are reused.

When catalysts are reused in such a process scheme, it may be desirableto employ the catalysts in a higher concentration than they are employedin a single-pass process. This may result in faster reactions, orsmaller process equipment, which results in lower capital costs for theequipment employed.

In a continuous recycle process, undesirable impurities and/or reactionbyproducts may build up in the process. Thus, it is desirable to providea means for removing such impurities from the process, such as via oneor more purge outlets, for example, or by a separation step.Furthermore, a purged stream may be further treated to recover a usefulportion of the purged stream.

The chlorinating agent that may optionally be present in the mixturetreated according to the present invention is preferably hydrogenchloride or hydrogen chloride source, and may be a gas, a liquid or in asolution, or a mixture thereof. The hydrogen chloride is preferablyintroduced in the gaseous state and, when the hydrochlorination reactionmixture is in the liquid phase, at least some of the hydrogen chloridegas is preferably dissolved in the liquid reaction mixture. The hydrogenchloride may, however, be diluted in a solvent, such as an alcohol (forexample methanol), or in a carrier gas such as nitrogen, if desired.

It is preferred that the hydrochlorination step of the present inventionbe carried out under superatmospheric pressure conditions.“Superatmospheric pressure” herein means that the hydrogen chloride(HCl) partial pressure is above atmospheric pressure, i.e. 15 psia (103kPa) or greater. Generally, the hydrogen chloride partial pressureemployed in the hydrochlorination process is at least about 15 psia (103kPa) or greater. Preferably, the hydrogen chloride partial pressureemployed in the hydrochlorination process is not less than about 25 psia(172 kPa), more preferably not less than about 35 psia (241 kPa), andmost preferably not less than about 55 psia (379 kPa); and preferablynot greater than about 1000 psia (6.9 MPa), more preferably not greaterthan about 600 psia (4.1 MPa), and most preferably not greater thanabout 150 psia (1.0 MPa).

It is also preferred to conduct the hydrochlorination step at atemperature sufficient for hydrochlorination that is also below theboiling point of the chlorohydrin(s) in the reaction mixture having thelowest boiling point for a given pressure condition during thehydrochlorination step in order to keep the chlorohydrin(s) produced andconverted during hydrochlorination in the liquid phase of the reactionmixture for recovery in steps (b) and (c). The upper limit of thispreferred temperature range may be adjusted by adjusting the pressurecondition. A higher pressure during hydrochlorination may be selected toincrease the boiling point temperature of the chlorohydrin(s) in thereaction mixture, so that the preferred temperature range for keepingDCH(s) in the liquid phase may be increased by increasing the pressurecondition.

Preferably, less than 50, more preferably less than 10, even morepreferably less than 5, and yet more preferably less than 1, percent ofthe DCH present in the hydrochlorination effluent is removed from thehydrochlorination effluent prior to step (b).

The hydrochlorination effluent comprises one or more DCHs, one or morecompounds comprising ester(s) of DCH(s), MCH(s) and/or ester(s) thereof,and MAHC(s) and/or ester(s) thereof, and optionally one or moresubstances comprising water, chlorination agent(s), catalyst(s) and/orester(s) of catalyst(s). Additional optional components may also bepresent in the effluent depending on the starting materials, reactionconditions, and any process steps intervening between thehydrochlorination reaction and recovery of DCH according to the presentinvention. The hydrochlorination effluent is preferably in the liquidphase as the hydrochlorination effluent is withdrawn from thehydrochlorination step and/or reactor and the mixture provided in step(a) comprises at least part of the liquid-phase effluent of thehydrochlorination step.

In a preferred embodiment, at least one MAHC and/or ester thereof ispresent in the mixture provided in step (a). When MAHC(s) and/orester(s) thereof is/are present in the mixture provided in step (a), thesame MAHC(s) and/or ester(s) thereof may also be present in thehigh-boiling fraction of step (b).

MAHCs found in the effluent treated according the present invention mayinclude for example 1,2-ethanediol; 1,2-propanediol; 1,3-propanediol;3-chloro-1,2-propanediol; 2-chloro-1,3-propanediol; 1,4-butanediol;1,5-pentanediol; cyclohexanediols; 1,2-butanediol;1,2-cyclohexanedimethanol; 1,2,3-propanetriol (also known as, and usedherein interchangeable as, “glycerin”, “glycerine”, or “glycerol”); andmixtures thereof. Preferably, the MAHCs in the effluents treatedaccording to the present invention include for example 1,2-ethanediol;1,2-propanediol; 1,3-propanediol; and 1,2,3-propanetriol; with1,2,3-propanetriol being most preferred.

Examples of esters of MAHCs found in the effluents treated according tothe present invention include for example ethylene glycol monoacetate,propanediol monoacetates, glycerin monoacetates, glycerin monostearates,glycerin diacetates, and mixtures thereof. In one embodiment, suchesters can be made from mixtures of MAHC with exhaustively esterifiedMAHC, for example mixtures of glycerol triacetate and glycerol.

In the same or another preferred embodiment, at least one MCH and/orester thereof is present in the mixture provided in step (a). WhenMCH(s) and/or ester(s) thereof is/are present in the mixture provided instep (a), the same MCH(s) and/or ester(s) thereof may also be present inthe high-boiling fraction of step (b).

The MCHs generally correspond to the hydrochlorinated MAHCs in which oneof a pair of hydroxyl groups covalently bonded to two separate vicinalcarbon atoms is replaced by a covalently bonded chlorine atom. Theester(s) of MCH may be the result of hydrochlorination of MAHC ester(s)or reaction with an acid catalyst, for example.

The DCHs generally correspond to the hydrochlorinated MAHCs in which twohydroxyl groups covalently bonded to two separate carbon atoms, at leastone of which is vicinal to a third carbon atom having a hydroxyl group,are each replaced by a covalently bonded chlorine atom. The ester(s) ofDCH(s) may be the result of hydrochlorination of MAHC ester(s), MCHester(s) or reaction(s) with acid catalyst(s), for example.

In an embodiment of the present invention where MAHC(s) is/are thestarting material fed to the process, as opposed to ester(s) of MAHC(s)or a mixture of MAHC(s) and ester(s) thereof as a starting material, itis generally preferred that the formation of chlorohydrin be promoted bythe presence of one or more catalyst(s) and/or ester(s) thereof.Catalyst(s) and/or ester(s) thereof may also be present where ester(s)of MAHC(s), or a mixture of MAHC(s) and ester(s) thereof, is a startingmaterial to further accelerate the hydrochlorination reaction.

Carboxylic acids, RCOOH, catalyze the hydrochlorination of MAHCs tochlorohydrins. The specific carboxylic acid catalyst chosen may be basedupon a number of factors including for example, its efficacy as acatalyst, its cost, its stability to reaction conditions, and itsphysical properties. The particular process, and process scheme in whichthe catalyst is to be employed may also be a factor in selecting theparticular catalyst. The “R” groups of the carboxylic acid may beindependently chosen from hydrogen or hydrocarbyl groups, includingalkyl, aryl, aralkyl, and alkaryl. The hydrocarbyl groups may be linear,branched or cyclic, and may be substituted or un-substituted.Permissible substituents include any functional group that does notdetrimentally interfere with the performance of the catalyst, and mayinclude heteroatoms. Non-limiting examples of permissible functionalgroups include chloride, bromide, iodide, hydroxyl, phenol, ether,amide, primary amine, secondary amine, tertiary amine, quaternaryammonium, sulfonate, sulfonic acid, phosphonate, and phosphonic acid.

The carboxylic acids useful as hydrochlorination catalysts may bemonobasic such as acetic acid, formic acid, propionic acid, butyricacid, isobutyric acid, hexanoic acid, 4-methylvaleric acid, heptanoicacid, oleic acid, or stearic acid; or polybasic such as succinic acid,adipic acid, or terephthalic acid. Examples of aralkyl carboxylic acidsinclude phenylacetic acid and 4-aminophenylacetic acid. Examples ofsubstituted carboxylic acids include 4-aminobutyric acid,4-dimethylaminobutyric acid, 6-aminocaproic acid, 6-hydroxyhexanoicacid, 6-chlorohexanoic acid, 6-aminohexanoic acid, 4-aminophenylaceticacid, 4-hydroxyphenylacetic acid, lactic acid, glycolic acid,4-dimethylaminobutyric acid, and 4-trimethylammoniumbutyric acid.Additionally, materials that can be converted into carboxylic acidsunder reaction conditions, including for example carboxylic acidhalides, such as acetyl chloride, 6-chlorohexanoyl chloride,6-hydroxyhexanoyl chloride, 6-hydroxyhexanoic acid, and4-trimethylammonium butyric acid chloride; carboxylic acid anhydridessuch as acetic anhydride and maleic anhydride; carboxylic acid esterssuch as methyl acetate, methyl propionate, methyl pivalate, methylbutyrate, ethylene glycol monoacetate, ethylene glycol diacetate,propanediol monoacetates, propanediol diacetates, glycerin monoacetates,glycerin diacetates, glycerin triacetate, and glycerin esters of acarboxylic acid (including glycerin mono-, di-, and tri-esters); MAHCacetates such as glycerol 1,2-diacetate; carboxylic acid amides such asε-caprolactam and γ-butyrolactam; and carboxylic acid lactones such asγ-butyrolactone, δ-valerolactone and ε-caprolactone may also be employedin the present invention Zinc acetate is an example of a metal organiccompound. Mixtures of the foregoing catalysts and catalyst precursorsmay also be used.

When a catalyst is used in the superatmospheric pressure process, thecatalyst may be for example a carboxylic acid; an anhydride; an acidchloride; an ester; a lactone; a lactam; an amide; a metal organiccompound such as sodium acetate; or a combination thereof. Any compoundthat is convertible to a carboxylic acid or a functionalized carboxylicacid under hydrochlorination reaction conditions may also be used. Apreferred carboxylic acid for the superatmospheric pressure process isan acid with a functional group consisting of a halogen, an amine, analcohol, an alkylated amine, a sulfhydryl, an aryl group or an alkylgroup, or combinations thereof, wherein this moiety does not stericallyhinder the carboxylic acid group.

Certain catalysts may also be advantageously employed atsuperatmospheric, atmospheric or sub-atmospheric pressure, andparticularly in circumstances where water is continuously orperiodically removed from the reaction mixture to drive conversion todesirably higher levels as may be the case when recovering DCH(s)according to the claimed invention. For example, the hydrochlorinationof MAHC(s) reaction can be practiced by introducing hydrogen chloridegas into contact with a mixture of MAHC(s) and catalyst(s), such as bysparging the hydrogen chloride gas through a liquid-phase reactionmixture. In such a process, the use of less volatile catalysts, such as6-hydroxyhexanoic acid, 4-aminobutyric acid; dimethyl 4-aminobutyricacid; 6-chlorohexanoic acid; caprolactone; carboxylic acid amides suchas ε-caprolactam and γ-butyrolactam; carboxylic acid lactones such asγ-butyrolactone, δ-valerolactone and ε-caprolactone; caprolactam;4-hydroxyphenyl acetic acid; 6-amino-caproic acid; 4-aminophenylaceticacid; lactic acid; glycolic acid; 4-dimethylamino-butyric acid;4-trimethylammoniumbutyric acid; and combination thereof; and the likemay be preferred. It is most desirable to employ a catalyst, under theseatmospheric or subatmospheric conditions, that is less volatile than theDCH(s) produced and recovered.

Preferred catalysts used in the present invention include carboxylicacids, esters of carboxylic acids, and combinations thereof,particularly esters and acids having a boiling point higher than that ofthe desired highest boiling DCH that is formed in the reaction mixture(i.e., the catalyst(s) is/are preferably less volatile than the DCH(s)in the mixture), so that the DCH(s) can be removed without removing thecatalyst. Catalysts which meet this definition and are useful in thepresent invention include for example, polyacrylic acid, glycerin estersof carboxylic acids (including glycerin mono-, di-, and tri-esters),polyethylene grafted with acrylic acid, divinylbenzene/methacrylic acidcopolymer, 6-chlorohexanoic acid, 4-chlorobutanoic acid, caprolactone,heptanoic acid, 4-hydroxyphenylacetic acid, 4-aminophenylacetic acid,6-hydroxyhexanoic acid, 4-aminobutyric acid, 4-dimethylaminobutyricacid, 4-trimethyl-ammoniumbutyric acid chloride, stearic acid,5-chlorovaleric acid, 6-hydroxyhexanoic acid, 4-aminophenylacetic acid,and mixtures thereof. Carboxylic acids that are sterically unencumberedaround the carboxylic acid group are generally preferred.

Furthermore, the catalyst(s) is/are preferably miscible with the MAHC(s)employed. For this reason, the catalyst(s) may contain polar heteroatomsubstituents such as hydroxyl, amino or substituted amino, or halidegroups, which render the catalyst miscible with the MAHC(s) in thereaction mixture, such as glycerol.

One embodiment of the catalyst(s) that may be present is generallyrepresented by Formula (a) shown below wherein the functional group “R′”includes a functional group comprising an amine, an alcohol, a halogen,a sulfhydryl, an ether; or an alkyl, an aryl or alkaryl group of from 1to about 20 carbon atoms containing said functional group; or acombination thereof; and wherein the functional group “R” may include ahydrogen, an alkali, an alkali earth or a transition metal or ahydrocarbon functional group.

Where the catalyst is recycled and used repeatedly, such recycledcatalysts may be present in an amount from about 0.1 mole %, preferablyfrom about 1 mole %, more preferably from about 5 mole %, up to about99.9 mole %, preferably up to 70 mol %, and more preferably up to 50mole %, based on the amount in moles of MAHC present. Higher catalystsconcentrations may be desirably employed to reduce the reaction time andminimize the size of process equipment.

In a preferred embodiment, the mixture distilled or fractionated in step(a) comprises water, such as the water produced as a co-product of thehydrochlorination reaction, water present in the starting materials forthe hydrochlorination reaction, and/or water introduced as the strippingagent. The mixture may contain at least 1 weight-percent, or at least 5weight-percent water, but less than the weight-percent of water at theazeotropic composition of the dichlorohydrin-water mixture or thedichlorohydrin-water-hydrogen chloride mixture at the distillationpressure, preferably up to 50 weight-percent, more preferably up to 20weight-percent, and most preferably up to 10 weight-percent water.

The mixture distilled or fractionated in step (a) may be a liquid phaseor a combination of liquid-phase and vapor phase. In one embodiment, themixture distilled or fractionated in step (a) is provided to step (a) byseparating a hydrochlorination reaction effluent stream into avapor-phase effluent stream and a liquid-phase effluent stream prior tostep (a) and introducing the liquid-phase effluent stream, or both thevapor-phase effluent stream and the liquid-phase effluent stream,separately or combined, into step (a). The separation of the reactioneffluent stream in step (a) of the process may be carried out in, forexample, in a separation system comprising a liquid-vapor contactingdevice and, optionally, with a flash vessel separate from or integralwith the liquid-vapor contacting device.

Recovery of DCH from the Mixture

Distilling/Fractionating Step(A)

Recovering DCH(s) from the mixture comprises distilling or fractionatingthe mixture under reflux conditions to separate from the mixture a firstvapor phase effluent stream comprising one or more of theabove-identified DCH(s) and water having a first temperature equal to orgreater than the boiling point of the DCH(s) and water present in themixture at the pressure of the first vapor phase effluent. The DCH(s)preferably comprise(s) 1,3-dichloro-2-propanol and/or2,3-dichloro-1-propanol).

The first vapor phase effluent stream may contain one or more of theabove-identified MCH(s), such as 2-chloro-1,3-propanediol and/or3-chloro-1,2-propanediol, and ester(s) thereof; one or more of theabove-identified MHAC(s); and/or one or more of the above-identifiedsubstances comprising chlorinating agent(s), catalyst(s), and/orester(s) of catalyst(s). Distilling or fractionating step (a) enrichesthe concentration of DCH(s) in the first vapor phase effluent streamrelative to the mixture fed to the distilling or fractionating step.

Distillation or fractionation step (a) is preferably carried out at atemperature measured in the distillation bottoms of at least 25° C.,more preferably at least 50° C., yet more preferably at least 80° C.,even more preferably at least 100° C., and yet even more preferably atleast 110° C., up to 160° C., preferably up to 150° C., even morepreferably up to 140° C., yet even more preferably up to 130° C., andmost preferably up to 120° C. The lower temperatures help minimize therate of formation of the higher molecular weight compounds, calledheavies, in the process and conversely, the higher temperatures increasethe rate of formation of the heavies. The lower bottom temperature alsoreduces the risk of a runaway reaction in the case of a process upsetsuch as loss of vacuum or loss of power to the plant.

One method of achieving low temperature in the bottom of the column isoperating the column under a vacuum condition such that the pressure inthe top of the column is maintained at less than 100 kPa, preferablyless than 50 kPa, more preferably less than 10 kPa, and most preferablyless than 5 kPa and greater than 0.1 kPa, preferably greater than 0.5kPa and most preferably greater than 1 kPa. Lower pressure in the columnhelps achieve lower temperature in the bottom of the column, but thismust be balanced with increased column size as well as increasedoperating cost required at lower pressures. Increased column sizeresults in increased capital cost of the column and the columninternals.

To one embodiment of the process of the present invention step (a) iscarried out at a pressure in the range from 0.1 kPa to 100 kPa;preferably, in the range from 1 kPa to 20 kPa; and about preferably inthe range from 1 kPa to 10 kPa.

The preferred reduced pressure condition may be generated by applyingvacuum directly or indirectly to the mixture undergoing distillation orfractionation in step (a) to produce the first vapor-phase effluentstream. The vacuum is preferably applied to the third vapor-phaseeffluent stream downstream from the second cooling step (e). The vacuumis preferably applied using any appropriate means for generating vacuum,such as a vacuum pump or a steam ejector.

The percent DCH(s) recovered from the mixture fed into step (a)generally depends on the combination of temperature and pressureconditions selected. To obtain a given DCH recovery in step (a), areduction in temperature generally requires a reduction in operatingpressure and, conversely, an increase in operating pressure generallyrequires an increase in operating temperature to obtain a given percentDCH recovery rate. The specific temperature and pressure conditionsselected will depend on the extent to which realization of therespective benefits relating to low temperature and higher pressureoperation is desired.

Step (a) is preferably carried out under conditions such that the amountof heavy byproducts in the high boiling fraction of step (a) does notexceed 120 percent, more preferably does not exceed 110 percent, evenmore preferably does not exceed 105 percent, and most preferably doesnot exceed 102 percent of the amount of heavy byproducts in the mixturefed into step (a). Minimizing the heavy and undesired byproductsformation in the process allows reducing the process purge required toprevent buildup of heavy byproducts in the process when operating theprocess as a continuous recycle process. The purge stream may containusable components in the process such as dichlorohydrins,monochlorohydrins, MAHCs, catalyst, and/or their esters. Therefore,minimizing the purge results in increased yield of dichlorohydrins.

When the chlorinating agent is hydrogen chloride, for example, most ofthe hydrogen chloride is removed from the mixture during step (a),because it is lighter (i.e., has a lower boiling point or has a highervapor pressure) than water, chlorohydrin(s), heavies, etc., of the feedstream fed to step (1).

The feed stream provided in step (a) may be passed through a pressureletdown step prior to distilling and/or fractionating the mixture, suchas via an intervening flash vessel, to reduce the pressure of the streamand flashing tendency during distillation and/or fractionation. Theflash vessel may act also as a surge or a buffer vessel to reduce impactof flow fluctuations or surges upstream from the distillation and/orfractionation step, and help regulate the flow of the mixture into thedistillation and/or fractionation step at a relatively constant rate.

The distillation or fractionation step (a) is preferably carried out inat least one liquid-vapor contacting device, such as at least onedistillation or fractionation column (preferably one fractionaldistillation column and/or a packed column), preferably having a sourceof heat at the bottom end of the liquid-vapor contacting device and ameans for applying a vacuum to the top end of the liquid-vaporcontacting device. Examples of distillation columns suitable for use asthe liquid-vapor contacting device include plate or tray columns, bubblecap columns and packed columns. The liquid-vapor contacting device isoperated under reflux conditions.

In one embodiment, additional MAHC(s) and/or ester(s) thereof may beintroduced into step (a) for reactive distillation/fractionation. Theadditional MAHC(s) and/or ester(s) thereof may react with thechlorination agent to produce additional MCH(s) and/or ester(s) thereof.Additional MAHC(s) may also react with ester(s) of DCH(s) and MCH(s) toconvert them to non-ester(s) to facilitate recovery of DCH(s). Theadditional MAHC(s) and/or ester(s) thereof is/are preferably introducedas a liquid phase into a reflux to provide additional liquid phase forreflux.

The mixture fed into step (a) is distilled or fractionated in step (a)to separate a first vapor-phase effluent comprising at least DCH(s) andwater from the liquid-phase mixture of step (a). The first vapor-phaseeffluent of step (a), which may also contain other low-boiling orazeotropic components of the mixture fed into step (a), such as thechlorinating agent, is condensed to form a first condensed liquid-phaseeffluent stream comprising at least DCH(s) according to step (b). Thefirst condensed liquid-phase effluent stream is separated into a firstfraction and a second fraction. The first fraction of the firstcondensed liquid-phase effluent stream is recycled to the distilling orfractionating step (a) according to step (d). Recycling the firstfraction of step (c) according to step (d) provides liquid for refluxduring distillation or fractionation according to step (a).

Partially Condensing the First Vapor-Phase Effluent

The DCH-rich first vapor phase effluent produced via distilling orfractionating the above-described mixture under reflux conditionsaccording to step (a) is cooled nonadiabatically to a second temperaturelower than the first temperature of step (a) to condense a fraction ofthe first vapor phase effluent stream of step (a) to produce a firstcondensed liquid-phase effluent stream and a second vapor phase effluentstream having the second temperature.

The second temperature of step (b) is below the dew point of the firstvapor-phase effluent stream at the operating pressure of step (b) andpreferably greater, more preferably at least 1 degree Celsius greater,than the dew point of water at the operating pressure of step (b). Thesecond temperature is preferably at least 5° C., more preferably atleast 10° C., and most preferably at least 20° C., and up to 60° C.,more preferably up to 50° C., and even more preferably up to 40° C.,below the first temperature of step (a).

In one embodiment, step (b) is conducted using a first nonadiabaticcooling device, such as an evaporative condenser or a water-cooledcondenser, using water from a cooling pond and/or a fluid coolingmedium, such as water, used upstream as the fluid cooling medium in thesecond cooling step (e). It is advantageous to select the secondtemperature such that the nonadiabatic cooling can be provided by waterfrom a cooling pond or cooling tower instead of using chilled water.This saves energy that is otherwise required in refrigeration when usingchilled water and accomplishes the cooling with minimum energy use.

The first vapor-phase effluent stream comprises organic compounds andwater and optionally the chlorinating agent.

The first condensed liquid-phase effluent stream contains more than 50weight-percent, preferably more than 60 weight-percent, more preferablymore than 70 weight-percent, even more preferably more than 80 weightpercent, yet even more preferably more than 90 weight-percent, mostpreferably more than 95 weight-percent and yet even more preferably morethan 99 weight-percent, DCH(s). The high purity DCH(s), such as 99weight-percent DCH(s), that can be obtained allows using such DCH(s)without requiring any further purification in a process where highpurity DCH(s) is preferred or required. The high purity DCH can beadvantageously used directly (i.e., preferably without any interveningpurifying unit operations, more preferably without any intervening unitoperations) in epoxidation of Bisphenol to produce liquid epoxy resin.

In step (d), the first fraction of the first condensed liquid-phaseeffluent stream produced in step (b) is recycled to step (a) as refluxfor step (a). The ratio of mass flow rate of the first fraction of thefirst condensed liquid-phase effluent stream recycled to step (a) asreflux for step (a) relative to mass flow rate of the total firstcondensed liquid-phase effluent stream condensed during step (b) ispreferably at least 0.1:1 and up to 0.8:1, preferably up to 0.5:1, morepreferably up to 0.4:1, and even more preferably up to 0.3:1. In oneembodiment, the ratio is for the range of from 0.1:1 to 0.4:1. Thisratio determines the reflux ratio for the column.

When using packed columns and low reflux ratios which results in lowreflux rates, it is desirable to employ liquid distributors that aresuitable for low liquid loading. Liquid loading is defined as liquidmass flow rate per unit cross sectional area of the distillation orfractionation column DCHs have much lower heat of vaporization comparedwith water. Therefore if aqueous-rich liquid is used for reflux in thedistillation column instead of the DCH-rich organic liquid, then thereflux ratio would be even smaller which would result in even smallerliquid flow rates from the liquid distributor requiring special liquiddistributors that are suitable for such low liquid loading. Therefore,using DCH rich liquid for reflux according to the present inventionprovides greater choice in the design and selection of the appropriateliquid distributor. This greater choice is especially advantageous in acorrosive process such as this process.

The first condensed liquid-phase effluent stream is preferablyaccumulated prior to recycling it into step (a) to facilitate goodcontrol/optimization of the reflux flow rate over time and therebyreduce fluctuations in step (a) operating conditions and/or first vaporphase effluent output. The accumulation is preferably conducted by meansof a reservoir between step (b) and step (c) as further described belowwith reference to the illustrative drawings.

Partially Condensing the Second Vapor-Phase Effluent Stream

The second vapor phase effluent stream of step (b) is cooled, preferablynon-adiabatically, to a third temperature lower than the secondtemperature of the second vapor phase effluent stream to condense atleast a fraction of the second vapor phase effluent stream of step (b)to produce a second condensed liquid-phase effluent stream and a thirdvapor phase effluent stream having the third temperature,

In the process for recovering DCH(s) according to the present invention,the third temperature of cooling step (e) is preferably below, morepreferably at least 1 degree Celsius below, and even more preferably atleast 5 degrees Celsius below, the dew point of water at the operatingpressure of cooling step (e). The third temperature is preferably atleast 10° C., more preferably at least 20° C., and even more preferablyat least 30° C. below the second temperature of cooling step (b). Thethird temperature is preferably selected such that at least 80 masspercent, more preferably at least 90 mass percent, even more preferablyat least 95 mass percent and most preferably at least 99 mass percent ofthe second vapor phase effluent stream is condensed to achieve thehighest total recovery of DCH(s).

In one embodiment, step (e) is conducted using a cooling device, such asthe cooling device described above as suitable for use in step (b). Thefluid cooling medium may be water from a cooling pond if it is availableat a low enough temperature and/or a refrigerated fluid cooling mediumsuch as chilled water or chilled glycol, or the refrigerant itself. In apreferred embodiment, chilled water or chilled glycol or such lowtemperature coolants are used to obtain a high recovery of DCHs.

The volumetric ratio of the first condensed liquid-phase produced instep (b) to the second condensed liquid-phase produced in step (e) ispreferably at least 1:1, more preferably at least 3:1, even morepreferably at least 5:1, up to 100:1, more preferably up to 50:1, andeven more preferably up to 40:1.

In one embodiment, the ratio of the mass flow rate at which the firstvapor-phase effluent stream is condensed in step (b) to the mass flowrate at which the second vapor-phase effluent stream is condensed instep (e) is in the range from 1:1 to 100:1; preferably in the rangesfrom 1:1 to 10:1; and where preferably in the range from 1:1 to 2:1.

Processing the Condensed Liquid-Phase Effluent Streams Downstream

The second fraction of the first condensed liquid phase effluent streamproduced during step (b) and separated in step (c) may be subjected tofurther processing steps. Depending on the further processing steps, thesecond fraction may be used to supply DCH(s) for chemical conversion ofDCH(s) into other compounds without further processing. The liquid phasemay be used in processes for conversion of DCH(s) into otherindustrially useful chemical products.

The second fraction separated in step (c) may, for example, be subjectedto epoxidation to form epichlorohydrin without additional purificationof the dichlorohydrin(s). The epoxidation may be carried out bycontacting one or more effluent streams comprising DCH(s) with a base,such as alkali metal hydroxide (e.g., sodium hydroxide) or alkalineearth metal hydroxide (e.g., calcium hydroxide or calcium carbonate) toform epichlorohydrin(s) and alkali metal chloride salt(s) or alkalineearth metal chloride salt(s), respectively.

In one embodiment, the second condensed liquid-phase effluent streamcomprises an aqueous phase and an organic phase. Phase separation in theliquid generating an aqueous rich and an organic rich phases depends onthe concentration of HCl in the liquid, the temperature and the overallcomposition of the liquid. Phase separation is most prone to occur whenHCl concentration in the liquid is lower. In the case of phaseseparation, the organic phase and the aqueous phase of the secondcondensed liquid-phase effluent stream are preferably separated fromeach other, so that the flow and composition of the two phases to thedownstream process can be controlled at relatively constant values forbetter control in the downstream process or they may be used separatelydownstream. In particular, the separated aqueous phase may be used inthe epoxidation step to recover and convert DCH(s) remaining in theseparated aqueous phase as well as to provide additional water formaintaining concentration of salts below saturation condition in theepoxidation step.

The separated organic phase obtained from the second condensedliquid-phase effluent stream may be used in a downstream epoxidationprocess to supply additional recovered DCH(s) independent from, orpreferably combined with, the use of the second fraction of the firstcondensed liquid-phase effluent stream in a downstream epoxidationprocess. In one embodiment, the organic phase obtained from the secondcondensed liquid-phase effluent stream is combined, or admixed, with thesecond fraction of the first condensed liquid-phase effluent stream andthe combined effluent streams are subjected to epoxidation as describedabove.

Separation of the aqueous phase and the organic phase may be carried outusing a liquid-liquid separation device such as those conventional inthe art. An example of a liquid-liquid separation device is a decanter.

Variations and Advantages

The Above Process Steps May Be Carried Out Independently OrSimultaneously with one another. In a preferred embodiment, one or moreof the above process steps is carried out simultaneously with oneanother.

One or more of the above process steps may be carried out continuouslyor discontinuously. One or more of the above process steps arepreferably carried out continuously (i.e., without interruption).Preferably, all the above process steps are carried out continuously.The process may be carried out for a predetermined period of time, forexample for a time period of about one hour or more.

The process according to the present invention may recover at least 80percent, more preferably at least 90 percent, even more preferably atleast 95 percent, yet more preferably at least 99 percent, and yet evenmore preferably at least 99.9 percent of the DCH(s) produced duringhydrochlorination.

These high recovery rates are obtained at a greater efficiency than thatobtained using state of the art methods. The process is more energyefficient because first condenser can use cooling water and only thesecond condenser may require chilled water or chilled glycol or suchother appropriate coolant. Therefore, it is preferred to maximize thecondensation in the first of the two partial condensers.

Using DCH-rich liquid for reflux instead of water-rich liquid makes theliquid distributor design and selection easier as the reflux flow rateis not too small A very small reflux flow rate requires speciallydesigned liquid distributors in the distillation column which can bevery expensive in a highly corrosive process such as this as it requireshighly specialized materials of construction. Using DCH-rich liquid forreflux to increase the reflux mass flowrate is achieved withoutrequiring more energy for distillation of DCH(s).

Apparatus

The above process may be conducted using an apparatus according to thepresent invention. The apparatus is now described in more detail inreference to FIG. 1.

FIG. 1 is a schematic diagram showing the main features of anillustrative apparatus that may be used and their respective feedstreams. The apparatus of FIG. 1 for producing DCH, generally indicatedby numeral (10), comprises a reactor system generally indicated bynumeral (30) comprising one or more reactors (31) connected in series orin parallel. The reactors may be selected from various known reactors,such as CSTRs, tubular reactors, and PFRs, and combinations thereof.When multiple reactors are present, the reactors may be connected toeach other in series or parallel. The reactor system (30) is connecteddirectly or indirectly to a first feed stream (32) comprising MAHC(s)and a second feed stream (33) comprising chlorinating agent.

The reactor system (30) is connected directly or indirectly to aseparation system generally indicated by numeral (40) for conducting atleast part of a liquid-phase reactor effluent feed stream (34) from thereactor system (30) to the separation system (40).

The separation system (40) comprises at least one liquid-vaporcontacting device (41) for distillation and/or fractionation of thereactor effluent feed stream (34) and optionally one or more flashvessels (not shown).

The liquid-vapor contacting device (41) preferably has a bottom endgenerally indicated by numeral (42) and a top end generally indicated bynumeral (43) for applying a gradually decreasing temperature gradientfrom the bottom end (42) to the top end (43) to substances within theliquid-vapor contacting device. The at least one liquid-vapor contactingdevice (41) of the at least one separation system (40) is preferably adistillation or fractionation column, such as a packed distillationcolumn and/or a distillation column adapted for carrying out fractionaldistillation under reflux conditions having a reflux zone for carryingout reflux.

The separation system (40) has a vapor phase effluent outlet for removalof vapor phase from the separation system (40), which is preferablylocated proximal to the top end (43) of the at least one liquid-vaporcontacting device (41), and a liquid phase effluent outlet for removalof liquid phase from the separation system (40), which is preferablylocated proximal to the bottom end (42) of the at least one liquid-vaporcontacting device (41).

The separation system (40) may comprise one or more flash vessels (notshown). The reactor system (30) is preferably connected to the at leastone liquid-vapor contacting device (41) of the at least one separationdevice (40) via the at least one flash vessel, whereby the reactoreffluent feed stream (34) is separated into a vapor phase and a liquidphase in the flash vessel by reducing the pressure on the liquid phase.The separated liquid phase and vapor phase may be introduced into the atleast one liquid-vapor contacting device (41) of the separation system(40) for distillation or fractionation.

The separation system (40) also preferably comprises a reboiler (notshown) connected to the bottom end (42) of the at least one liquid-vaporcontacting device (41) of the separation system (40) for heating theliquid phase in the bottom end (42) of the at least one liquid-vaporcontacting device (41) of the separation system (40).

The at least one liquid-vapor contacting device (41) of the separationsystem (40) is optionally connected directly or indirectly to at leastone source of stripping agent for introducing one or more strippingagents into the bottom end (42) of the at least one liquid-vaporcontacting device (41) of the separation system (40).

The separation system (40) is preferably connected to the reactor system(30) for conducting a distillation residue recycle stream (44, 45)comprising a distillation residue stream (44) from the separation system(40) to the reactor system (30). The recycle feed stream (44 45)preferably has a distillation residue recycle purge (46) for removal ofheavy byproducts from the distillation residue recycle feed stream (44,45).

The top end (43) of the liquid-vapor contacting device (41) is connectedto a first condensation system generally indicated by numeral (50)comprising a first cooling device (51) for conducting a vapor phaseeffluent stream (47) from the separation system (40) to the firstcondensation system (51).

The first condensation system (50) comprises a first cooling device (51)and, optionally, a first reservoir (52) connected to the first coolingdevice (51) for accumulation of condensate from the first cooling device(51).

The first cooling device (51) is a cooling device suitable for coolingthe vapor phase effluent stream (47) from a first temperature at orabove the dew point of the first vapor-phase effluent stream (47) to asecond temperature below the dew point of the first vapor-phase effluentstream (47) and above the dew point of water at the operating pressureof the cooling device (51). The first cooling device (51) is preferablya nonadiabatic cooling device.

The cooling device (51) is preferably one or more condensers. Thecondensers preferably comprise one or more coolant passages made ofheat-conductive material, for conducting a fluid, such as an aqueousliquid, having a temperature at or below the above-mentioned secondtemperature. The optional first reservoir (52) is preferably adapted toreceive condensate from one or more condensers of cooling device (51).

The first condensation system (50) is connected to the separation system(40) for recycling a fraction of condensed liquid-phase effluent stream(53) from the first condensation system (50) to the separation system(40) via a condensed liquid-phase recycle stream (54, 55). The condensedliquid-phase recycle stream (54, 55) is preferably conducted to at leastone liquid-vapor contacting device for distillation and/orfractionation. In particular, the condensed liquid-phase recycle stream(54, 55) is preferably conducted to the reflux of at least oneliquid-vapor contacting device, such as at least one distillation and/orfractionation column. The connection for recycling a fraction of acondensed liquid-phase effluent stream (53′) from the condensationsystem (50) to the separation system (40) preferably terminates proximalto the top end (43) of the at least one liquid-vapor contacting device(41).

The at least one liquid-vapor contacting device (51) preferablycomprises a liquid distributor (not shown) for distributing a condensedliquid-phase effluent stream (53) within the at least one liquid-vaporcontacting device (51). The liquid distributor is preferably locatedproximal to the location of the point(s) at which the recycle stream(53) is introduced into the at least one liquid-vapor contacting device(51) and is preferably an integral part of the liquid-vapor contactingdevice (51).

The first cooling device (51) is preferably connected to the separationdevice (41) via a first reservoir (52) for accumulating condensedliquid-phase produced by the first cooling device (51). The firstreservoir (52) is preferably connected to the at least one liquid-vaporcontacting device (41) of the separation device (40) for conducting arecycle stream (54, 55) from the first reservoir (52) to the at leastone liquid-vapor contacting device (41) of separation device (40) as asubstitute for a condensed liquid-phase recycle stream (53) conducteddirectly from the first cooling device (51) to the separation device(40).

The first reservoir (52) provides a means for decoupling the flow rateof the recycle stream (54, 55) from the flow rate of the condensateeffluent stream (53) produced by the at least one cooling device (51).Decoupling may be used to reduce or eliminate flow rate variations inrecycle stream (54, 55), so that recycle stream (54, 55) may beintroduced into separation device (40) at a relatively constant rate incomparison to the flow rate of the condensed liquid-phase effluentstream (53). The first reservoir may also function as a liquid-vaporseparator for enhancing separation of the liquid and vapors resultingfrom the first cooling device.

The fraction of the condensed liquid-phase effluent stream (53) inexcess of the fraction of the condensed liquid-phase effluent stream(53) recycled to separation device (40) is conducted as first productstream (54,56) from the first condensation system (50) to a storagevessel, another reservoir, or a reaction vessel for further processing.In one embodiment, the first product stream (54, 56) is conducteddirectly, or indirectly, to a dehydrochlorination reaction vesselsuitable for converting DCH to epichlorohydrin. The dehydrochlorinationreaction vessel is preferably suitable for contacting DCH with a base,such as an alkali metal, or alkaline earth metal, base, such as sodiumhydroxide or calcium hydroxide or carbonate, respectively, in thepresence of water, which is preferably in the liquid state.

A second condensation system generally indicated by numeral (60) isconnected to the first condensation system (50) for conducting thevapor-phase effluent stream (57) from first condensation system (50) tothe second condensation system (60) to form a second condensedliquid-phase product stream (61).

The second condensation system (60) comprises a second cooling device(61) and, optionally, a second reservoir (62) connected to the secondcooling device (61) for accumulation of condensate from the secondcooling device (61). The second reservoir may also function as aliquid-vapor separator for enhancing separation of the liquid and thevapors resulting from the second cooling device.

The second cooling device (61) is suitable for cooling the vapor phaseeffluent stream (57) to a third temperature, which is lower than thesecond temperature of second vapor-phase effluent stream, and preferablylower than the dewpoint of water, at the operating pressure of thesecond condensation system (60). The second cooling device (61) ispreferably a nonadiabatic cooling device.

The second cooling device (61) is preferably one or more condensers. Thecondensers preferably comprise one or more coolant passages made ofheat-conductive material for conducting a fluid cooling medium, such asan aqueous or glycolic liquid phase, having a temperature at or belowthe above-mentioned third temperature. The optional second reservoir(62) is preferably adapted to receive condensate from one or morecondensers of cooling device (61).

In one optional embodiment, the second cooling device (61) is connectedto the first cooling device (51) for conducting a fluid cooling medium,such as water, from the second cooling device (61) to the first coolingdevice (51), so that the fluid cooling medium heated by the secondnonadiabatic cooling device (61) is used as the fluid cooling medium inthe first cooling device (51) to reduce the demand for cooling medium.

The second condensed liquid-phase product stream (63) is conducted assecond product stream (63) from the second cooling device (61) to astorage vessel, another reservoir, or a reaction vessel for furtherprocessing. In one embodiment, the second condensed liquid-phase productstream (63) is conducted directly, or indirectly, to adehydrochlorination reaction vessel suitable for converting DCH toepichlorohydrin. The dehydrochlorination reaction vessel is preferablysuitable for contacting DCH with a base, such as an alkali metalhydroxide (e.g., sodium hydroxide) or alkaline earth metal hydroxide orcarbonate (e.g., calcium hydroxide), in the presence of water, which ispreferably in the liquid state

The dehydrochlorination reaction vessel may be, and preferably is, thesame dehydrochlorination reaction vessel as the dehydrochlorinationreaction vessel that may be connected to the first condensation system(50) via the first liquid-phase product stream (54, 56).

The second cooling device (61) is preferably connected to a secondreservoir (62) for conducting the second condensed liquid-phase productstream (63) from the second cooling device (61) to the second reservoir(62). The second reservoir (62) provides a means for decoupling the flowrate of the second liquid-phase product stream (65) from flow ratevariations in second condensed liquid-phase effluent stream (63) forintroducing the second condensed liquid-phase product stream (65) intothe next unit operation, such as a reactor, at a controlled or constantrate in comparison to the flow rate of the condensed liquid-phaseeffluent stream (63) in a manner analogous to the function of the firstreservoir (52).

The third vapor phase effluent stream (64) may be conducted from thesecond cooling device (61) to another unit operation, such as aliquid-vapor contacting device (e.g., a scrubber) for removing and/orrecycling chlorinating agent, such as hydrogen chloride gas and/orhydrochloric acid.

A second embodiment of an apparatus of the invention for producing DCHis shown in FIG. 2, and generally indicated by numeral (20). Theembodiment of the apparatus shown in FIG. 2 is the same as in FIG. 1except that in the apparatus (20), the second condensation system (60)is connected to a liquid-liquid phase separator (66). The liquid-liquidphase separator (66) separates a liquid aqueous phase (68) from a liquidorganic phase (67). The liquid-liquid phase separator (66) may, forexample, be a decanter.

The liquid organic phase effluent stream (67) from the liquid-liquidphase separator (66) may be stored or conducted to another unitoperation, such as a dehydrochlorination reactor, and/or combined withliquid-phase product stream (56) for storage or further processing aspreviously described above for liquid-phase product stream (56).

The liquid aqueous phase effluent stream (68) from the liquid-liquidphase separator (66) may be used in a downstream dehydrochlorinationreactor to recover and convert DCH(s) remaining in the separated aqueousphase and to provide process water to the above-mentioneddehydrochlorination reactor for maintaining chloride salts, such asalkali metal chloride salt(s) or alkaline earth metal chloride salt(s),produced by reacting DCH with an alkali metal or alkaline earth metalbase, below their saturation limit in the liquid to keep the salts fromprecipitating.

The remainder of FIG. 2, including the definitions of apparatuscomponents and streams, is substantially the same as in FIG. 1.

In each of FIGS. 1 and 2, vapor-phase stream (64) is preferablyconnected, directly or indirectly, to a downstream vacuum generatingdevice (not shown) for reducing the pressure of the vapor phase withinthe apparatus below atmospheric pressure. The vacuum generating deviceis preferably downstream of the optional unit operation for removingchlorinating agent, such as the liquid-vapor contacting device used as ascrubber described above. The vacuum-generating device is preferably avacuum pump or steam ejector.

To the extent that components of the above apparatus are exposed tocorrosive materials, such components are preferably fabricated ofmaterials which are resistant to corrosion by the process components.Kirk-Othmer Encyclopedia of Chemical Technology, 2^(nd) Edition (JohnWiley and Sons, 1966), volume 11, pages 323-327, presents an extensivediscussion of the corrosion resistance of metals and non-metals that canbe used in hydrochloric acid and hydrogen chloride service. Specificexamples of suitable materials are disclosed in WO 2006/020234. Specificexamples include metals such as tantalum, suitable metallic alloys(particularly nickel-molybdenum alloys such as Hastalloy C©), orglass-lined, plastic-lined or graphite equipment.

The following examples are for illustrative purposes only and are notintended to limit the scope of the present invention.

Equipment Used in the Examples Example 1

Distillation is carried out using a glass distillation column packedwith 6 mm ceramic Intalox saddles containing two packed bed sections.Feed to the column is located between the two packed bed sections. Thecolumn is provided with a glass reboiler and two partial condensers inseries, also made of glass, for cooling the vapor stream exiting thecolumn. The first condenser is located directly on top of the column andwas cooled with chilled glycol. A portion of the condensate from thefirst condenser is returned to the column as reflux and the rest of thecondensate is collected as product.

Uncondensed vapors from the first condenser are condensed in the secondcondenser operating at a lower temperature and cooled with chilledglycol. The uncondensed vapors exiting the second condenser are passedthrough a set of cold traps before entering the vacuum pump whichprovides vacuum to the whole system. The second condensed liquid-phaseeffluent from the second condenser enters a liquid-liquid separator.Under the process conditions used in this example, only a small amountof liquid organic phase is occasionally separated from the substantiallyaqueous second condensed liquid-phase effluent.

In this example, a DCH recovery process is conducted according to thepresent invention based on the distillation column process conditionsshown in Table 1 below:

TABLE 1 Distillation Column Process Conditions Units Pressure at the topof the column 1.6 kPa Temperature at the top of the column 50 ° C. Firstcondenser temperature 15 ° C. Second condenser temperature 0 ° C.Fraction of 1^(st) condenser product recycled to 0.25 the column forreflux

The distillation data is shown in Table 2.

TABLE 2 First condenser product 2^(nd) Second condenser Subject Feedfraction product Vent Bottoms Units Fraction of feed to the column 10.39 0.01 balance 0.59 H₂O 8.9 20.1 56.6 — wt. % HCl 3.3 7.2 21.9 — wt.% 1,3-dichloro-2-propanol 33.1 70.8 21.1 7.4 wt. %2,3-dichloro-1-propanol 7.1 1.8 0.3 11.0 wt. % other components 47.6 — —81.6 wt. %

In Table 2 alone and its subsequest tables,

“Feed” refers to stream (34) in FIG. 1;

“First condenser product” refers to stream (56) in FIG. 1;

“Second condenser product” refers to stream (63) in FIG. 1;

“Vent” refers to the third vapor phase stream (64) in FIG. 1;

“Bottoms” refers to the distillation residue stream (44) of FIG. 1; and

a hyphen (“-”) indicates that the weight-percent value is below 0.01.

Table 2 above shows that the feed stream to the distillation columncomprising dichlorohydrins is separated into a top product streamcomprising primarily dichlorohydrins and a bottom product streamcomprising the heavier components in the feed stream such as MCH,glycerol and other components including the catalyst and its esters,ethers and higher molecular weight compounds, often called heavies. Thefirst product stream from the first condenser contains primarily DCHs asshown in the example above whereas the second product stream from thesecond condenser is a water-rich aqueous stream. The measurementsprovided in Table 2 above are within experimental measurement error ofabout +/−3 percent relative error.

Example 2

Distillation is carried out, using a glass lined distillation columnpacked with graphite packing, containing two packed bed sections. Feedto the column is located between the two packed bed sections. The columnis provided with a reboiler and two partial condensers in series, madeof graphite, for cooling the vapor stream exiting the column. The firstcondenser is cooled with cooling water. A portion of the condensate fromthe first condenser is returned to the column as reflux and the rest ofthe condensate is collected as product.

Uncondensed vapors from the first condenser are condensed in the secondcondenser operating at a lower temperature and cooled with chilledglycol. The uncondensed vapors exiting the second condenser are passedto the steam ejector vacuum pump which provides vacuum to the wholesystem. The second condensed liquid-phase effluent from the secondcondenser is collected in an intermediate vessel as product. Themeasurements provided in Table 2 above are within experimentalmeasurement error of about +/−5 percent relative error.

Table 3 below provides some of the key operating conditions in theequipment:

TABLE 3 Distillation Column Process Conditions Units Pressure at the topof the column 4.5 kPa Temperature at the top of the column 67 ° C. Firstcondenser temperature 45 ° C. Second condenser temperature 10 ° C.Fraction of 1^(st) condenser product recycled to 0.5 the column forreflux

The distillation data is shown in Table 4.

TABLE 4 First condenser product - 2^(nd) Second condenser Subject Feedfraction product Vent Bottoms Units Fraction of feed to the column 10.17 0.16 balance 0.63 H₂O 6.2 2.8 40.7 — wt. % HCl 2.5 1.3 12.5 — wt. %1,3-dichloro-2-propanol 34.9 90.4 44.9 16.9 wt. %2,3-dichloro-1-propanol 7.6 5.5 1.9 9.4 wt. % other components 48.8 — —73.7 wt. %

Table 4 above shows that the feed stream to the distillation columncomprising dichlorohydrins is separated into a top product streamcomprising primarily dichlorohydrins and a bottom product streamcomprising the heavier components in the feed stream such as MCHs,glycerol and other components which include the catalyst and its esters,ethers and higher molecular weight compounds, often called heavies. Thefirst product stream from the first condenser contains greater than 95weight percent DCHs as shown in the example above whereas the secondproduct stream from the second condenser contains high concentrations ofboth DCHs and water.

Example 3

This example is based on a computer simulation of the process usingcommercially available software and physical properties andthermodynamic models of the major components. Table 5 provides keyprocess conditions in the equipment and Table 6 provides mass flow ratesand compositions for the feed and the product streams.

TABLE 5 Distillation Column Process Conditions Units Pressure at the topof the column 4.5 kPa Temperature at the top of the column 68 ° C. Firstcondenser temperature 45 ° C. Second condenser temperature 10 ° C.Fraction of 1^(st) condenser product recycled to 0.43 the column forreflux

The computer model-generated distillation results are shown in Table 6.

TABLE 6 First condenser product - 2^(nd) Second condenser Subject Feedfraction product Vent Bottoms Units Fraction of feed to the column 10.15 0.18 balance 0.67 H₂O 7.0 0.75 38.7 — wt. % HCl 3.0 — 16.9 — wt. %1,3-dichloro-2-propanol 33.2 96.4 43.4 17.2 wt. %2,3-dichloro-1-propanol 1.4 2.8 1.0 1.3 wt. % other components 55.4 — —81.5 wt. %

The results shown in Table 6 (from a computer simulation) are similar tothe results shown in Table 4 from an experiment. The first productstream from the first condenser in Table 6 contains greater than 99weight percent dichlorohydrins.

What is claimed is: 1.-17. (canceled)
 18. An apparatus suitable forproducing dichlorohydrin(s) from multihydroxylated-aliphatic hydrocarboncompound(s) and/or ester(s) thereof comprising: (1) a reactor systemsuitable for carrying out hydrochlorination of multi-hydroxylatedaliphatic hydrocarbon compound(s) and/or ester(s) thereof comprising oneor more reactors connected in series or in parallel; (2) a separationsystem comprising at least one liquid-vapor contacting device suitablefor distillation of a reactor effluent stream obtainable from thereactor system and, optionally, at least one flash vessel; (3) a firstcondensation system comprising a first cooling device and optionally afirst reservoir connected to the cooling device for accumulation ofcondensate from the first cooling device; and (4) a second condensationsystem comprising a second cooling device and optionally (a) a secondreservoir connected to the second cooling device for accumulation ofcondensate from the second cooling device and/or (b) a liquid-liquidphase separation device connected to the second cooling device forseparating a liquid phase comprising aqueous and organic components intoan aqueous phase and an organic phase separate from the aqueous phase;wherein the at least one reactor system is connected to the separationsystem for conducting a reactor effluent stream from the reactor systemto the separation system for distillation and/or fractionation of thereactor effluent stream; the separation system is connected to the firstcondensation system for conducting a first vapor-phase distillationand/or fractionation effluent stream from the separation system to thefirst condensation system; the first condensation system is connected tothe second condensation system for conducting a second vapor-phaseeffluent stream from the first condensation system to the secondcondensation system; and the first condensation system is connected tothe separation system for conducting a fraction of a first condensedliquid-phase effluent stream from the first condensation system to theseparation system.
 19. The apparatus according to claim 18, wherein thefirst cooling device of the first condensation system is located on topof the at least one liquid-vapor contacting device of the separationdevice; or wherein the first cooling device is an integral part of theat least one liquid-vapor contacting device.
 20. The apparatus accordingto claim 18 further comprising a means for applying a vacuum, directlyor indirectly, to the at least one liquid-vapor contacting device forreducing the pressure in the liquid-vapor contacting device belowatmospheric pressure; and wherein the means for applying a vacuum islocated downstream from the second condensation system.
 21. Theapparatus according to claim 18, wherein the at least one liquid-vaporcontacting device is a packed distillation column; or wherein the atleast one liquid-vapor contacting device is a distillation columnadapted for carrying out fractional distillation under refluxconditions.
 22. The apparatus according to claim 18, wherein the atleast one liquid-vapor contacting device is connected to the reactorsystem for conducting a recycle stream from the bottom end of the atleast one liquid-vapor contacting device to the reactor system.
 23. Theapparatus according to claim 18, wherein the one or more reactors of thereactor system comprises a plug flow reactor.
 24. The apparatusaccording to claim 21, wherein the first condensation system isconnected to a second reactor suitable for conductingdehydrochlorination for conducting a first condensed liquid-phaseeffluent stream from the first condensation system to the secondreactor; wherein the second condensation system is connected to thesecond reactor suitable for conducting dehydrochlorination forconducting a second condensed liquid-phase effluent stream from thesecond condensation system to the second reactor; wherein the secondcondensation system comprises a liquid-liquid phase separation devicefor separating a liquid aqueous phase from a liquid organic phase andthe second cooling device of the second condensation system is connectedto the liquid-liquid phase separation device for conducting a condensedliquid-phase from the second cooling device to the liquid-liquid phaseseparation device; and wherein the liquid-liquid phase separationdevice, is connected to the second reactor suitable for conductingdehydrochlorination for conducting an organic liquid-phase effluentstream and/or an aqueous liquid phase effluent stream from theliquid-liquid phase separation device to the second reactor.